Resiliently mounted swingable side plates for loading machines and the like

ABSTRACT

A loading machine is disclosed having a main frame and a swing frame connected to the main frame for pivotal movement about horizontal and vertical axes, the main frame and swing frame each having laterally spaced upstanding side panels thereon which define channel means through which material may pass, and wherein side plates are pivotally and resiliently supported to substantially close off and prevent passage of material through the spacing between adjacent ends of the side panels as the swing frame pivots relative to the main frame, the side plates also serving to absorb impact forces from material which passes through the channel means and strikes the side plates.

Unite States Patent [191 Kamner RESHLIENTLY MOUNTED SWINGABLE SlllDE PLATES FOR LOADING MACHINES AND THE LIKE Haim J. Kamner, Palatine, lll.

Goodman Equipment Corporation, Chicago, 111.

Filed: Dec. 13, 1972 Appl. No.: 314,812

Inventor:

Assignee:

US. Cl. 198/95, 214/140 lint. Cl. B65g 37/00 Field of Search 198/109, 31 AC, 95;

References Cited UNITED STATES PATENTS Primary Examiner-Robert J. Spar Assistant Examinerlohn Mannix Attorney, Agent, or Firm-Fitch, Even, Tabin & Luedeka 5 7 ABSTRACT A loading machine is disclosed having a main frame and a swing frame connected to the main frame for pivotal movement about horizontal and vertical axes, the main frame and swing frame each having laterally spaced upstanding side panels thereon which define channel means through which material may pass, and wherein side plates are pivotally and resiliently supported to substantially close off and prevent passage of material through the spacing between adjacent ends of the side panels as the swing frame pivots relative to the main frame, the side plates also serving to absorb impact forces from material which passes through the channel means and strikes the side plates.

8 Claims, 4 Drawing Figures RESILIENTLY MOUNTED SWINGABLE SIDE PLATES FOR LOADING MACHINES AND THE LIKE The present invention relates generally 'to loading machines and the like, and more particularly to novel means for preventing passage of loaded material through variable width spaces between adjacent ends of side panels which define material passage means along a main frame and a pivotal swing fraine.

It is a conventional practice in the mining industry, and particularly in underground tunnel mining, to employ relatively large size loading machines, often termed muckers, to load loose material which has been broken way from the vertical face or wall of the tunnel. The loading machines are employed to pick up the piles of loose material and convey the material to transport cars which transport the mined material from the mine. Such loading machines are well known and are commercially available under the trade name CONWAY MUCKERS from Goodman Equipment Corporation, Chicago, 111., the assignee of the present invention. These loading machines include a main frame and a forward swing frame or boom which is connected to the main frame for movement about both vertical and horizontal axes. The boom carries a digging mechanism, such as a bucket assembly, on its forward end which may be advanced into a muck pile by crowding and :rooting."

The main frame and forward swing frame have laterally spaced generally upstanding side panels thereon which define channel means through which the loose material passes when the bucket assembly is raised to dump material from the bucket onto a belt conveyor provided on the forward swing frame. The swing frame is pivotable about the vertical pivot axis while the main frame remains generally stationary so as to provide access to piles of loose fly-rock disposed on either side of the longitudinal axis of the main frame. Because the swing frame is frequently pivotally swung to either side of the longitudinal axis of the main frame during operation, spaces of varying size are created between the vertical edge surfaces of the adjacent side panels on the main frame and swing frame such that material being loaded may pass outwardly through the spaces as the material is conveyed rearwardly to the hauling cars. The present invention provides novel means for closing off the variable width spaces between the adjacent ends of the side panels to prevent passage of loaded material therethrough.

One of the primary objects of the present invention is to provide novel means for preventing spillage of loaded material through variable width spaces between adjacent ends of side panels on a loading machine or the like.

Another object of the present invention is to provide side plates on a loading machine to prevent spillage of loaded material through variable spacings between adjacent ends of side panels on the machine, wherein the side plates are pivotally and resiliently mounted so as to continually close off the variable spacings and absorb impact forces from material striking the side plates as it is conveyed between the upstanding side panels.

Still another object of the present invention is to provide novel means for mounting a pair of laterally spaced side plates between upstanding side panels on a main frame and a swing frame of a loading machine or the like, wherein each side plate is mounted on a pair of leaf springshaving first end portions pivotally connected to an associated hinge post secured on the swing frame, with the opposite ends of the leaf springs being slidingly cooperable with guide rails mounted on the corresponding side panels on the main frame to prevent spillage between the side panels throughout full pivotal movement of the swing frame relative to the main frame.

Further objects and advantages of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying; drawings, wherein like reference numerals designate like elements throughout the several views and wherein:

FIG. 1 is a side elevational view of a loading machine having side plates mounted thereon in accordance with the present invention;

FIG. 2 is an enlarged partial side view of the mining machine of FIG. 1, portions being broken away for clarity, and the swing frame being swung to an extreme pivotal position relative to the main frame;

FIG. 3 is a partial plan view of the machine as illustrated in FIG. 2, the swing frame being shown in an opposite pivotal position relative to the longitudinal axis of the main frame; and

FIG. 4 is a partial vertical sectional view taken gener ally along the line 4-4 of FIG. 2.

Referring now to the drawings, and in particular to FIG. 1, the present invention is illustrated, by way of example, in conjunction with a loading or mining machine indicated generally at 10. The loading machine 10 comprises a mobile railway type vehicle having track-engaging wheels 12 for movement of the vehicle along parallel spaced track rails 14 as may be provided on the floor or ground surface of a tunnel under construction, or in an underground mine. The loading machine 10 includes a main frame, indicated generally at 16, which is supported directly by the wheels 12, and a forward swing frame or conveyor boom, indicated generally at 18, which is supported by the main frame 16 for movement about horizontal and vertical axes as will be described more fully below.

The main frame 16 includes drive means operatively associated with the wheels 12 for effecting selective movement of the loading machine 10 along the rails 14. The main frame 16 supports a rearwardly extending, upwardly inclined conveyor assembly, indicated generally at 20, which is adapted to convey material received from the forward swing frame or boom 18 to a rearward hauling vehicle or transport car (not shown) in a known manner. To this end, the conveyor assembly 20 includes an endless conveyor belt, indicated at 22 in FIG. 3, which is reeved about drive drums (not shown) and extends from the uppermost end of the conveyor assembly 20 to a position disposed below the rearward end of the forward swing frame 18 so that material, such as fly-rock and the like, will drop onto the lower forward end of the conveyor belt 22 from the rearward end of the swing frame 18 during a loading operation. The main frame 16 also includes a pair of laterally spaced, generally parallel upstanding side panels 24 which comprise mirror images of each other and are mounted forwardly of the center of the longitudinal length of the main frame 16. The side panels 24 define channel or trough means therebetween and serve to assist in guiding materials passed upwardly along the conveyor assembly from the forward swing frame 18.

The swing frame 18 includes a boom assembly comprising a pair of laterally spaced parallel beams 26 which are secured by transverse cross members in fixed relation and have bifurcated rearward end portions 28. The bifurcated end portions 28 of the beams 26 are secured onto the opposite ends of a transverse pivot shaft 30 which is slidingly received through and supported within aligned bearing bores in a pair of laterally spaced upstanding support blocks 32. The support blocks 32 are mounted on a pivot frame 34 which is pivotal about a vertical axis 36 (FIG. 3) in a known manner such that the swing frame 18 is adapted by pivotal movement about both horizontal and vertical axes relative to the main frame 16.

A loading bucket or shovel assembly, indicated generally at 38, is supported on the forward or outermost end of the swing frame 18 and is adapted to pick up loose material, such as fly-rock and the like, from piles of loose material disposed forwardly of and laterally on either side of the longitudinal axis of the main frame 16. The material is then dumped from the bucket assembly onto an endless conveyor belt, indicated at 40 in FIG. 3, on the swing frame 18. Thereafter, the material is moved rearwardly on the swing frame conveyor belt 40 and passes onto a downwardly inclined pan plate 42 from which the material drops or slides onto the belt conveyor 22 on the main frame 16. The bucket assembly 38 is of known construction and includes a shovel element 44 pivotally connected to the forward ends of a pair of laterally spaced support brackets 46 which are fixedly secured on the forward ends of the beams 26. A pair of double acting fluid cylinders 48 are selectively operable to effect movement of the shovel element 44 through bell crank lever members 49 to effect pivotal movement of the shovel element during operation, in a known manner.

The swing frame 18 includes a pair of laterally spaced, parallel upstanding side panels 50 which are mounted in generally vertical upstanding relation on the beams 26 of the swing frame. The side panels 50 extend from a position rearwardly of the support blocks 32 longitudinally along the associated beams 26 to the forward end of the swing frame 18 adjacent the bucket assembly 38. The side panels 50 define channel or trough means therebetween for the passage of material picked up by the bucket assembly 38 and deposited on the forward end of the conveyor belt 40.

A pair of double acting fluid actuating cylinders 52 and 53 are mounted on the main frame 16 and are selectively operable in a known manner to effect pivotal movement of the swing frame 18 about the vertical axis 36 and about the horizontal axis defined by pivot shaft 30.

The loading machine 10 thus far described is of known construction and is commercially available from the assignee of the present invention. The loading machine 10 is described herein as being but one example of a machine on which the present invention may be employed. As will become apparent hereinbelow, the present invention finds application with any machine having first and second pivotally connected frame. sections wherein one frame section is pivotally movable relative to the other frame section, and wherein the frame sections have upstanding side panels thereon defining channel passage means through which loose materials may be selectively passed.

The upstanding side panels 24 on the main frame 16 have vertical forward edge surfaces 24a which are disposed generally adjacent rearward upstanding edge surfaces a on the side panels 50 on the swing frame 18. It will be understood that when the swing frame 18 is pivotally swung to either side of the longitudinal axis of the main frame 16 about the vertical pivotal axis 36, the spacing between the edge surfaces 24a and 500 will vary depending upon the angular position of the swing frame relative to the main frame. The present invention is directed to means for preventing passage or spillage of loose material through the variable spacing between the adjacent edge surfaces 240 and 50a of the upstanding panels 24 and 50, respectively, as the swing frame 18 is pivoted about its vertical pivot axis 36 between its extreme pivotal positions relative to the main frame 16.

To this end, the loading machine 10 includes closure means, indicated generally at 54, mounted on both sides of the longitudinal axis of the loading machine for substantially closing the variable width spaces between the side panels 24 on the main frame 16 and the corresponding side panels 50 on the swing frame 18. Each closure means 54 includes a flat side plate 56 having a quadrilateral side profile configuration, as shown in FIG. 2. A lower edge surface 58 of each of the side plates 56 is angularly disposed relative to the inclined pan plate member 42 so as to prevent interference between the pan plate and either of the side plates 56 throughout the full range of pivotal movement of the swing frame 18 relative to the main frame 16. Each of the side plates 56 is mounted on and between a corresponding pair of the upstanding side panels 24 and 50 by resilient mounting meanscomprising a pair of vertically spaced parallel leaf springs 60. Each of the leaf springs 60 includes an inner leaf spring element 60a, and intermediate or center leaf spring element 60b slightly greater in length than the inner leaf spring, and an outer mounting'leaf spring element 600. The inner, center and outer leaf spring elements 60a, 60b and 600, respectively, are secured together in assembled relation with the associated side plate 56 by a spring mounting bracket 62 which is affixed to the associated side plate centrally of its horizontal width as by bolts 64. The mounting brackets 62 serve both to maintain the leaf spring elements 60a, 60b and 600 in assembled relation as well as secure the leaf spring assemblies to their associated side plates 56.

The outer mounting leaf spring elements 60c of each pair of leaf springs 60 have forward end portions pivotally connected to an associated hinge post 66 which is secured in vertical upstanding relation to an associated one of the support blocks 32 through mounting bolts 68. Each of the hinge posts 66 has a pair of vertically spaced support brackets 70 secured thereto which serve to support a vertical hinge pin 72 upon which is mounted a hinge tube 74 for rotational movement relative to the hinge pin 72. The forward ends of each pair of the outer mounting leaf springs 60c are secured to an associated one of the hinge tubes 74 through suitable mounting brackets 76 and bolts 78. In this manner, each pair of leaf springs 60 is adapted for rotation about the axis of the associated hinge pin 72 during pivotal movement of the forward swing frame 18 about its vertical pivotal axis 36.

The end of each of the outer mounting leaf springs 60c opposite its pivotal connection to the hinge pin 72 is cooperable with the associated side panel 24 to allow sliding guided movement of the leaf springs 60 relative to the fixed side panels 24 during pivotal movement of the swing frame 1%. To this end, each of the side panels 24 has upper and lower parallel horizontal plates 80 and 82, respectively, which have elongated guide rails 84 secured to their inner opposing surfaces such that the guide rails are parallel and lie in a common vertical plane. The guide rails 84 extend from adjacent the forward vertical edge surfaces 24a of the side panels 24 rearwardly substantially the full horizontal dimensions of the side panels 24.

A vertically disposed tubular hinge bar 86 is mounted between each pair of guide rails 84 for sliding movement along the associated guide rails through hinge pins 88 which are rotatably received within the opposite ends of each tubular hinge bar 86 and have spaced parallel guide plates 90 secured thereon to receive the guide rails 84 therebetween in sliding relation. In this manner, each of the hinge bars 86 is slidable along its associated guide rails $4 while being maintained in a vertical position. The rearward ends of each pair of outer leaf spring elements 60c are secured to the associated hinge bar 86 through mounting brackets 92 and mounting bolts 94 in similar fashion to the mounting of the forward ends of the outer mounting leaf spring elements We to the hinge tube 74.

Each of the hinge posts 66 has a generally planar flange plate portion 98 which extends rearwardly with its inner surface in planar relation with the inner surface of the associated support block 32 on the pivot frame 34. The relative horizontal dimensions of the flange plate portions 98 and the associated side plates 56 of the closure means 54 are such that a forward vertical edge 56a on each side plate 56 extends slightly forwardly of and outwardly from the rearward vertical edge surface 98a on the associated flange 98 through out full pivotal movement of the swing frame 18. To prevent passage of rock or coal fines through the gaps between the rearward vertical edges 98a of the flanges 98 and the forward vertical edges 56a of the side plates 56, flexible rubber plate members 104 having vertical heights generally equal to the vertical heights of the associated hinge posts 66 are secured to the flange portions 98 of the associated hinge posts as by mounting bolts 102. Each flexible plate 100 is adapted to engage its associated side plate 56 when the angle between the associated side panel 24 on the main frame 16 and the forward side panel 50 on the swing frame 18 forms an abtuse angle, considered from within the channel or trough passage means defined between the spaced side panels through which material is caused to pass during operation.

Having thus described a preferred embodiment of the closure means 54 operatively associated with the side panels 24 on the main frame 16 and the upstanding side panels 50 on the swing frame 18 of the loading machine 10, their operation will now be briefly reviewed. With the swing frame 18 disposed in a position wherein its longitudinal axis is substantially aligned with the longitudinal axis of the main frame 16, as illustrated in FIG. 1, the rearward ends of the outer mounting leaf spring elements are positioned to dispose the hinge bars 86 intermediate the lengths of the associated guide rails 84 on the side panels 24 of the main frame 16. When the swing frame 18 is pivoted about its vertical pivot axis 36 to a position such as illustrated in FIG. 3, the rearward ends of the leaf springs 60 associated with the side plate 56 on the side of the loading machine wherein the spacing between the side panels 24 and 50 is increased are moved forwardly on the guide rails 84 to allow the side plate to close off the relatively large space created between the associated side panels 24 and 50. Correspondingly, the rearward ends of the leaf springs 60 associated with the side plate 56 on the opposite side of he loading machine will be moved to a position wherein their associated hinge bar 86 is disposed adjacent the rearward ends of the corresponding guide rails 84.

With the side plates 56 in their respective positions as shown in FIG. 3, loose material such as rocks and the like which is moved rearwardly on the swing frame conveyor belt 40 and deposited onto the pan plate 42 for downward movement onto the main frame conveyor belt 22 is prevented from passing through the spaces between the vertical edge surfaces 24a and 50a on the side panels 24 and 50, respectively, by the side plates 56. The leaf spring elements 60a, 60b and 60c are preferably made of a suitable steel material, such as A181 5160 steel. If any rocks or other materials, which may weigh upwardly of 2 tons, strike the hinge plates 56, the associated leaf springs 60 absorb the impact forces and prevent damage to the side panels 24. Thus, the leaf spring mounting means for the side plates 56 provide pivotal mounting for the associated side plates 56 and serve to absorb impact loads from rocks striking the side plates.

It can thus be seen that the present invention provides closure means which serve to prevent passage of loose material through spacings between adjacent edge portions of relatively movable side panels, which spacing may vary depending upon the relative positions of the fixed and movable panels, such as may be provided on a main frame and a pivotal swing frame in a loading machine as above described. While the present invention has been described in connection with a loading or mining machine, it will be understood that the present invention may find application on other apparatus employing relatively movable main and swing frames along which materials may be passed and wherein spacing is normally existent between adjacent ends of side panels which define channel means through which the material is passed.

While a preferred embodiment of the present invention has been illustrated and described, it will be obvious to those skilled in the art that changes and modifications may be made therein without departing from the invention in its broader aspects. Various features of the invention are defined in the following claims.

I claim:

1. In a loading machine or the like having a main frame and a swing frame connected to said main frame for pivotal movement about a generally vertical axis adjacent one end of said main frame, said main frame and said swing frame each having laterally spaced generally upstanding side panels defining channel means there between along which material may pass, said side panels having adjacent end surfaces spaced apart a first distance when the swing frame is disposed in one pivotal position relative to the longitudinal axis of the main frame and being spaced apart a second lesser distance when the swing frame is disposed in an opposite pivotal position relative to said main frame; the combination therewith of relatively rigid side plates, and mounting means including at least one elongated spring fixedly secured to each of said side plates and resiliently mounting each of said side plates in upstanding relation between said main and swing frames such that each side plate is positioned to substantially close off and prevent passage of material through the space between the adjacent end surfaces of the associated side panels throughout the full range of pivotal movement of said swing frame relative to said main frame, said elongated springs being disposed between each of said side plates and said main and swing frames that loads impacting said side plates as material passes through said channel means are substantially absorbed by said resilient mounting means.

2. The combination of claim 1 wherein said side plates are generally flat, and wherein each of said springs has one end thereof pivotally secured to said swing frame in a manner to maintain the associated side plates in close proximity to the adjacent end surfaces of the associated side panels throughout pivotal movement of said swing frame about said generally vertical axis.

3. The combination of claim 2 wherein the opposite end of each of said elongated springs is slidingly secured to the associated side panel on said main frame.

4. The combination of claim 1 wherein said side plates are generally flat, and wherein said mounting means comprises a pair of leaf springs secured to each" of said side plates, the leaf springs of each of said pair of leaf springs being substantially parallel and having first end portions pivotally secured to said swing frame, the opposite ends of each pair of leaf springs being secured to the associated side panel on said main frame for sliding relation therewith.

5. The combination as defined in claim 1 including a pair of laterally spaced upstanding hinge posts fixedly mounted on said swing frame generally adjacent said pivotal connection of said swing frame to said main frame, and wherein said mounting means includes a pair ofielongated springs secured to each of said side plates, each pair of said springs having first end portions pivotally connected to and supported by an associated one of said hinge posts.

6. The combination as defined in claim 5 wherein said side panels on said main frame have guide track means thereon disposed generally parallel to the longitudinal axis of said main frame, and wherein the ends of said elongated springs opposite said pivotal connection thereof to said hinge posts are cooperatively associated with said guide track means for a sliding relation thereon.

7. The combination of claim 6 wherein said elongated springs comprise leaf springs secured to the associated side plates generally intermediate the widths of said side plates.

8. In a loading machine or the like having a main frame and a swing frame connected to said main frame for pivotal movement about a generally vertical axis adjacent one end of said main frame, said main frame and said swing frame each having laterally spaced generally upstanding side panels defining channel means therebetween along which material may pass, said side panels having adjacent end surfaces spaced apart a first distance when the swing frame is disposed in one pivotal position relative to the longitudinal axis of the main frame and being spaced apart a second lesser distance when the swing frame is disposed in an opposite pivotal position relative to said main frame; the combination therewith of a pair of side plates, mounting means including a pair of elongated springs secured to each of said side plates, a pair of laterally spaced upstanding hinge posts fixedly mounted on said swing frame generally adjacent said pivotal connection of said swing frame to said main frame, each pair of said springs having a first end portion pivotally connected to and supported by an associated one of said hinge posts and resiliently mounting the associated side plate in upstanding relation between said main and swing frames such that each side plate is positioned to substantially close off and prevent passage of material through the space between the adjacent end surfaces of the associated side panels throughout the full range of pivotal movement of said swing frame relative to said main frame, said elongated springs being adapted to absorb impact loads from material which passes through said channel means and strikes said side plates, each of said side plates having a generally vertical edge portion adapted to remain laterally outwardly of the associated hinge post throughout the full range of pivotal movement of said swing frame about said generally vertical axis, and including a flexible flap member secured to each of said hinge posts and adapted to sealingly engage the associated side plate when the angle between the longitudinal axis of said swing frame and the longitudinal axis of said main frame is abtuse, considered from within said channel means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Ina-5.842.964 Dated October 22, 1974 Invent fl HAIM J. KAMNER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line 12, after "frames" insert --such--.

Signed and sealed this 18th day of March 1975..

(SEAL) Attest:

C. MARSHALL DANN Commissioner of Patents and Trademarks RUTH C. MASON Attesting Officer 'ORM PO-105O (1M9) USCOMM-DC 6O376-P69 u.s. GOVERNIIINT PRIN'IING OFFIC! use o-ane-su. 

1. In a loading machine or the like having a main frame and a swing frame connected to said main frame for pivotal movement about a generally vertical axis adjacent one end of said main frame, said main frame and said swing frame each having laterally spaced generally upstanding side panels defining channel means therebetween along which material may pass, said side panels having adjacent end surfaces spaced apart a first distance when the swing frame is disposed in one pivotal position relative to the longitudinal axis of the main frame and being spaced apart a second lesser distance when the swing frame is disposed in an opposite pivotal position relative to said main frame; the combination therewith of relatively rigid side plates, and mounting means including at least one elongated spring fixedly secured to each of said side plates and resiliently mounting each of said side plates in upstanding relation between said main and swing frames such that each side plate is positioned to substantially close off and prevent passage of material through the space between the adjacent end surfaces of the associated side panels throughout the full range of pivotal movement of said swing frame relative to said main frame, said elongated springs being disposed between each of said side plates and said main and swing frames that loads impacting said side plates as material passes through said channel means are substantially absorbed by said resilient mounting means.
 2. The combination of claim 1 wherein said side plates are generally flat, and wherein each of said springs has one end thereof pivotally secured to said swing frame in a manner to maintain the associated side plates in close proximity to the adjacent end surfaces of the associated side panels throughout pivotal movement of said swing frame about said generally vertical axis.
 3. The combination of claim 2 wherein the opposite end of each of said elongated springs is slidingly secured to the associated side panel on said main frame.
 4. The combination of claim 1 wherein said side plates are generally flat, and wherein said mounting means comprises a pair of leaf springs secured to each of said side plates, the leaf springs of each of said pair of leaf springs being substantially parallel and having first end portions pivotally secured to said swing frame, the opposite ends of each pair of leaf springs being secured to the associated side panel on said main frame for sliding relation therewith.
 5. The combination as defined in claim 1 including a pair of laterally spaced upstanding hinge posts fixedly mounted on said swing frame generally adjacent said pivotal connection of said swing frame to said main frame, and wherein said mounting means includes a pair of elongated springs secured to each of said side plates, each pair of said springs having first end portions pivotally connected to and supported by an associated one of said hinge posts.
 6. The combination as defined in claim 5 wherein said side panels on said main frame have guide track means thereon disposed generally parallel to the longitudinal axis of said main frame, and wherein the ends of said elongated springs opposite said pivotal connection thereof to said hinge posts are cooperatively associated with said guide track means for a sliding relation thereon.
 7. The combination of claim 6 wherein said elongated springs comprise leaf springs secured to the associated side plates generally intermediate the widths of said side plates.
 8. In a loading machine or the like having a main frame and a swing frame connected to said main frame for pivotal movement about a generally vertical axis adjacent one end of said main frame, said main frame and said swing frame each having laterally spaced generally upstanding side panels defining channel means therebetween along which material may pass, said side panels having adjacent end surfaces spaced apart a first distance when the swing frame is disposed in one pivotal position relative to the longitudinal axis of the main frame and being spaced apart a second lesser distance when the swing frame is disposed in an opposite pivotal position relative to said main frame; the combination therewith of a pair of side plates, mounting means including a pair of elongated springs secured to each of said side plates, a pair of laterally spaced upstanding hinge posts fixedly mounted on said swing frame generally adjacent said pivotal connection of said swing frame to said main frame, each pair of said springs having a first end portion pivotally connected to and supported by an associated one of said hinge posts and resiliently mounting the associated side plate in upstanding relation between said main and swing frames such that each side plate is positioned to substantially close off and prevent passage of material through the space between the adjacent end surfaces of the associated side panels throughout the full range of pivotal movement of said swing frame relative to said main frame, said elongated springs being adapted to absorb impact loads from material which passes through said channel means and strikes said side plates, each of said side plates having a generally vertical edge portion adapted to remain laterally outwardly of the associated hinge post throughout the full range of pivotal movement of said swing frame about said generally vertical axis, and including a flexible flap member secured to each of said hinge posts and adapted to sealingly engage the associated side plate when the angle between the longitudinal axis of said swing frame and the longitudinal axis of said main frame is abtuse, considered from within said channel means. 